After three days of cloudwashing, cloud-in-a-box and erector set private cloud musings at Oracle OpenWorld in San Francisco this week, CEO Larry Ellison chose day four to take the wraps off a legitimate move into cloud computing.

Oracle Public Cloud is the unification of the company's long-struggling software-as-a-service (SaaS) portfolio with its Fusion applications transformation, all atop Oracle VM and Sun hardware. While Ellison spent much of his keynote taking pot shots at his former sales executive and now SaaS nemesis, Salesforce CEO Mark Benioff, the actual solution being delivered is more of a direct competitor to Amazon Web Services than Force.com. The strongest evidence is in Oracle's stance on multitenancy. Ellison adamantly shunned a tenancy model built on shared data stores and application models, which are key to the profitability of Salesforce.com (and most true SaaS and PaaS solutions), stating that security comes only through application and database isolation and tenancy through the hypervisor. Oracle will no doubt use its own Xen-based hypervisor, OracleVM rather than the enterprise standard VMware vSphere, but converting images between these platforms is quickly proving trivial.